1. The Field of the Invention
This invention relates to wells and, more particularly, to novel systems and methods for anchoring tubing within a well bore.
2. The Background Art
The presence of methane (CH4, a principal ingredient of natural gas) in underground coal seams has long been known. In the past, coal bed methane was vented to provide a non-explosive, non-suffocating environment in which coal miners could work. However, in recent times, methane has become a popular fuel for use in electric generators, furnaces, city buses, and the like. Methane's popularity may largely be attributed to its relatively low cost and clean combustion characteristics.
By drilling down to a coal seam aquifer and pumping out water, the pressure holding the methane within the coal seam may be relieved somewhat as it propels methane and water mixed therewith up the well bore (typically a cased bore). The methane may then be gathered, compressed, and shipped to customers. Well drilling and production techniques permit the collection of methane from coal seams at virtually all depths at which coal is available. Thus, coal bed methane may be collected from coal seams that are far too deep to be mined themselves.
In the past water and oil well technologies have been used to collect methane from coal seam aquifers. However, some of the equipment now in use is not optimal for the unique requirements of coal bed methane collection. For example, down-hole, tubing anchors developed for the oil industry do not have to deal with many of the annular flow demands found in coal bed methane extraction. When applied to a coal bed methane wells, typical anchors may limit gas production. What is needed is a down-hole tubing anchor specifically designed to handle annular flows, such as those found in coal bed methane wells.